Scientists have revealed that an anti-obesity drug changes the way the brain responds to appetizing, high-calorie foods in obese individuals. This insight may aid the development of new anti-obesity drugs which reduce the activity in the regions of the brain stimulated by the sight of tasty foods. This is not unexpected since the brain is the center of many such sensory responses. For example in 2008, researchers at Tufts University School of Medicine and colleagues demonstrated a link between a predisposition to obesity and defective dopamine signaling in the mesolimbic system in rats. The new study at the University of Cambridge discovered that the anti-obesity drug sibutramine reduced brain responses in two regions of the brain, the hypothalamus and the amygdala, both of which are known to be important in appetite control and eating behavior. Their findings are reported today in The Journal of Neuroscience.

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The brain is the center of the nervous system in all invertebrates and most invertebrates.

One of the primary functions of a brain is to extract
biologically relevant information from sensory inputs. Even in the human brain,
sensory processes go well beyond the classical five senses of sight, sound,
taste, touch, and smell: our brains are provided with information about
temperature, balance, limb position, and the chemical composition of the
bloodstream, among other things.

Professor Paul Fletcher, from the Department of Psychiatry
and the Behavioral & Clinical Neuroscience Institute at the University of Cambridge and one of the paper's
authors, said: "Currently, there are few drugs that effectively help
patients to lose weight. Developing new pharmaceuticals is expensive and risky.
However, our findings suggest that we may be able to use brain imaging and
psychological tests to make better predictions of which drugs are likely to
work."

Using functional magnetic resonance imaging the researchers
measured brain activity while obese volunteers viewed pictures of appetizing
high-calorie foods - like chocolate cake - or pictures of low-calorie foods -
like broccoli. The brain scanning was carried out both after two weeks of
treatment with the anti-obesity drug, sibutramine, and two weeks of placebo
treatment.

On placebo, it was shown that simply seeing pictures of
appetizing foods caused greater activation of many regions of the brain that
are known to be important for reward processing. On sibutramine, however, they
found that the anti-obesity drug reduced brain responses to the appetizing foods
in two regions of the volunteers' brain - the hypothalamus and the amygdala.
These two regions are known to be important in appetite control and eating
behavior. Additionally, people who had the greatest reduction of brain
activation following drug treatment tended to eat less and to lose more weight.

It has been said that the mind can rule over matter. In this case the mind can rule over the
desire for pleasure increasing high calorie food. A simple control technique such as shown in this
study may be very useful in the future on controlling appetite and hence
obesity.